Acceleration switch



Mardl 1965 w. T. SWINEHART ETAL 3,175,053

ACCELERATION SWITCH Filed Feb. 1, 1965 2 Sheets-Sheet 1 38 f 46 I2 44 40 5s 30 52 so 26 2a I6 42 l4 I8 50 54 32 6O 26 28 FIG. I

INVENTOR WILLIAM T SWINE HART BY iICHAEL W. DOYLE ATTORNEY March 23, 1965 Filed Feb. 1, 1963 W. T. SWINEHART ETAL ACCELERATION SWITCH 2 Sheets-Sheet 2 G2 FIG 6 GI ACCELERATION GI PROFILE INVENTOR.

T ME WILLIAM T SWINEHART BY MICHAEL W. DOYLE w w&

ATTORNEY United States Patent 3,175,058 ACCELERATIGN SWITCH William T. Swinehart, Scotts, and Michael W. Doyle,

Paw Paw, Mich, assignors to Pneumo Dynamics Corporation, Cleveland, Ohio, a corporation of Delaware Filed Feb. 1, 1963, Ser. No. 255,489 7 Claims. (Cl. 200-6145) This invention relates to a sequence acceleration sensor, and more particularly to a device for actuating a plurality of switches in succession according to a predetermined acceleration profile.

In projectiles, such as a missile, which is to be launched into space, it is necessary to produce an initial or a command signal, after launch, to perform a function, such as separating the nose cone from the engine after burn out. If the missile contains a warhead or some other type load, it may also be necessary to produce another subsequent or secondary command signal for arming the warhead, or activating the load, but as the case may be, the secondary command signal should not be produced until after certain conditions exist, such as the missile being safely away from the launching pad, until after the missile has attained a specific thrust, etc., etc. These command signals, as well as other types of controls, may be produced by actuating a plurality of switches in sequence as the missile reaches dilferent G-levels of acceleration.

Therefore, it is an object of the present invention to provide a sequence acceleration sensor for actuating a plurality of switches according to a predetermined acceleration profile.

An additional object of this invention is to provide a device for actuating a plurality of switches during the flight of a projectile wherein the device is operable in response to a predetermined acceleration profile of the projectile to sequentially actuate the switches.

It is also an object of this invention to provide a sequence acceleration sensor for a missile which is operable to sequentially actuate a plurality of switches in accordance with a predetermined acceleration porfile of the missile with the sensor being operable under unfavorable situations, such as the missile rotating or being out of control during flight.

Another object of this invention is to provide a sequence acceleration sensor that is reliable in operation, durable in use, simple to construct, and is inexpensive to manufacture.

A further object of this invention is to provide a sequence acceleration sensor for a projectile that may be easily set or reset for operation according to a desired, predetermined acceleration profile of the projectile.

Still another object of this invention is to provide a sequence acceleration sensor that will actuate a first device at a moment when the sensor has accelerated to a first value, and after the sensor has accelerated through a second value and has decelerated to a third value, the sensor will be operable to actuate a second device.

In order to accomplish and achieve the above stated objects, and overcome existing disadvantages of heretofore known devices of similar type, the instant inventive concept comprises an acceleration sensor for use in combination with projectiles, such as missiles, for sequentially actuating or controlling the performance and operation of certain desired functions associated with the flight of the projectile or missile with the sensor comprising a device having an elongate hollow housing, a mass supported within the hollow of the housing adjacent one end portion thereof with first biasing means urging the mass for longitudinal movement toward the other end portion of the housing, an actuator arm supported by the mass and pivotally carried thereon for generally laterally or transverse movement relative to the longitudinal axis of the housing, elongate guide means carried adjacent the other end portion of the housing and projecting generally longitudinally inwardly into the hollow thereof toward the mass with the guide means being disposed in laterally or transversely spaced relationship relative to the adjacent portion of the housing to define therewith a space disposed to the laterally or transversely opposed sides of the longitudinal axis of the housing. The actuator arm is initially positioned so as to extend into the space defined by the guide means and the adjacent portion of the housing to one side of the longitudinal axis whereat the actuator arm is operable to produce an initial or first command signal. On an increase in the acceleration of the missile or projectile to which the acceleration sensor device is operatively associated, a G-level is established and the mass is urged against the bias means in a direction toward the one end portion of the housing which results in the actuator arm being moved away from the guide means so that the initial command signal is eliminated and a second or intermediate command signal may be established. Further increase in the acceleration of the missile or projectile to a further and different G-level will urge the mass further toward the one end portion of the housing to a portion whereat the actuator arm clears the guide means and second biasing means is provided for urging the actuator arm to pivot generally laterally or transversely relative to the longitudinal axis of the housing and position the actuator arm to the other side or" the longitudinal axis whereat on a decrease in the acceleration, still another-and yet different G-level may exist so that the mass will be urged toward the guide means by reason of the first biasing means so that the actuator arm will then be positioned in the space to the other side of the longitudinal axis of the housing and engage the other side of the guide means and make addi tional sequential contacts threrealong to establish still other command signals, as desired.

Other objects, advantages and important features of the invention will be apparent from a study of the specification following, taken with the drawing, which together describe, disclose, illustrate and show a preferred embodiment of the invention, and what is now considered and believed to be the best method of practicing the principles thereof. Still other embodiments, modifications, procedures or equivalents may be subject to those having the benefit of the teaching herein and such other embodiments, modifications, procedures or equivalents are intended to be reserved especially as they fall within the scope and breadth of the subjoined claims.

In the drawing:

FIGURE 1 is a longitudinal side elevational sectional view of a sequence acceleration sensor according to the present invention, illustrating an actuator arm of the sen sor in a first or initial position;

FIGURE 2 is a fragmentary view of the acceleration sensor, illustrated in FIGURE 1, showing the sensor actuator arm in a second or intermediate position;

FIGURE 3 is a fragmentary view of the acceleration sensor, illustrated in FIGURE 1, showing the sensor actuator arm in a third position;

FIGURE 4 is an end elevational view of the acceleration sensor shown in FIGURE 1, taken along the line 44 and looking in the direction of the arrows;

FIGURE 5a is a schematic view showing first and second snap action type switches which may be actuated by the acceleration sensor, and illustrates the switch contacts for the first or initial position of the sensor actuator arm;

FIGURE 5!) is a schematic view, similar to FIGURE 50, showing the switches and the switch contacts for the second or intermediate position of the sensor actuator arm;

FIGURE c is a schematic view, similar to FIGURES 5a and 5b, showing the switches and the switch contacts for the third position of the sensor actuator arm, and

FIGURE 6 is a curve of gravitational force G versus time T for showing a predetermined acceleration profile for a projectile such as a missile.

Attention is now directed to FIGURE 1 of the drawing wherein a sequence acceleration sensor 16 is shown which is effective to sequentially actuate or control the performance and operation of certain desired functions, to be explained in more detail hereinafter, in response to a predetermined acceleration profile of a projectile, such as a missile, or the like, not illustrated, with the sensor 10 comprising a device having an elongate hollow housing 12 in which a mass structure 14 is positionedwith the mass structure 14- normally being disposed adjacent one end portion of the housing 12 and supported therein for longitudinal movement relative to the longitudinal axis AA of the housing with first biasing means 16 in the form of a coil spring urging the mass structure 14 toward the other end portion of the housing 12. An elongate actuator arm 18 is pivotally connected to the mass structure 14 by means 215 which may be in the form of a pivot pin, or the like, for generally lateral or transverse movement to each side of the longitudinal axis AA, and second biasing means 22 is provided for urging the actuator arm 18 to the opposed sides of the longitudinal axis AA.

Elongate guide means 24 is provided adjacent the other end portion of the housing 12 and the guide means 24 is preferably in the form of a wedge and projects generally longitudinally inwardly from the other end portion of the housing 12 into the hollow thereof toward the mass structure 14 with the guide means 24 being disposed generally along the longitudinal axis AA. The guide means 24 is provided with side portions 2626 which are laterally or transversely spaced from the adjacent portions of the housing 12 to define a space 23 therebetween with the side portions 26-26 converging toward each other and terminating in an apex 3t).

Snap action type switch devices 32, 34 are mounted to the side portions 26-26 of the guide means 2d, to opposite sides of the axis and positioned thereon for actuation of the actuator arm 18, as will be explained in more detail hereinafter.

The other end portion of the housing 12, note FIGURE 4 of the drawing, is provided with six terminals A, B, C, D, E and F for connecting external electrical leads to the switches 32 and 34 with the one end portion of the housing 12 having a cap screw 36 for closing an aperture through the end wall portion of the housing. Upon removal of the cap screw 36, a tool (not shown) may be inserted into the hollow of the housing 12 for adjusting the longitudinal position of the mass structure 14 to permit the lateral position of the actuator arm 18 to be changed relative to the guide means 24. A cap screw 38 is provided for closing another aperture through the side wall portion of the housing 12 and on removal of the cap screw 38, a tool (not shown) may be inserted into the hollow of the housing 12 for changing the lateral position of the actuator arm 18 against the lateral force produced by the biasing means 22.

The spring-loaded mass structure 14 comprises a piston-like member 411 and the helical spring 16. The piston-like member 46 slides freely along the inner side wall portion of the housing 12 in a generally longitudinal direction relative thereto along a given course that is substantially common with the axis AA thereof. Rotation of the piston-like member 411 relative to the housing 12 may be prevented by any suitable anti-rotation means, such as splines etc., or the like, not shown. The pistonlike member 41) is provided with a slotted recess 44 for receiving one end portion of the spring 16 with the other end portion of the spring 16 being in engagement with an embossed surface of a retaining plate 45 that fits within the inner end wall portion of the housing 12. Shim means 48 is inserted between the plate 46 and the one end portion of the housing 12 for adjusting the tension of the spring 16 to a predetermined value. The recess 44 in the piston-like member 411 is provided with a slot 42 that is aligned with the aperture that is closed by the cap screw 36 for receiving the end of a tool, not shown, for adjusting the longitudinal position of the piston-like member 40 relative to the housing 12.

The actuator arm 18 is pivotably mounted to the mass structure 14 by suitable means 20 such as a pivot pin, or the like, and the pin 20 is disposed generally transversely relative to the axis AA of the housing 12 and is secured to the piston-like member 40 by suitable means, not shown. The actuator arm 18 is accordingly adapted to pivot laterally or transversely of the given course AA and is adapted to mo e longitudinally relative thereto if there is relative motion between the pistonlike member 40 and the housing 12. In a first or initial position, as shown in FIGURE 1 of the drawing, the actuator arm 18 extends into a portion 59 of the space 28 defined by the wedge-shaped guide means 24 and the laterally adjacent portion of the housing 12 to depress a movable operating plunger 54 of the snap action type switch device 32. In a second or intermediate position as shown in FIGURE 2 of the drawing, the actuator arm 18 is withdrawn and is disposed adjacent the apex 3% of the guide means 24- with the plunger 54 of the switch device 32 being released. In a third or ultimate posi tion, as shown in FIGURE 3 of the drawing, the actuator arm 18 extends into another portion 52 of the space 28 between the wedge-shaped guide means 24 and the laterally adjacent portion of the housing 12 to depress a movable operating plunger 56 of the snap action type switch device 34-.

The second biasing means 22 is preferably in the form of an elongate torsion spring which is secured adjacent one end portion to the piston-like member 40. The other end portion of the spring 22 engages one side of the actuator arm 18. The force created by the spring 22 acts generally laterally or transversely relative to the longitudinal axis AA of the housing 12 and is sufficient to urge the actuator arm 18 from the first or initial position, FIG- URE 1 of the drawing, toward the third or ultimate position, FIGURE 3 of the drawing, when the actuator arm 18 clears the apex 31 of the guide means 24. To stop the lateral or transverse movement of the actuator arm 18 by the spring 22 after the actuator arm 18 is withdrawn from the space 5% to one side of the guide means 24, a stop 58 is provided which is secured to the housing 12 by any suitable means, not shown.

The guide means 24 is secured to the other end portion of the housing 12 by any suitable means, not shown. Machine screws 69 secure the snap action type switches 32 and 34 to respective side portions 2626 of the guide means 24. The apex 319 of the guide means 24 is preferably rounded, and is disposed slightly offset relative to the longitudinal axis AA of the housing 12. One of the inclined side portions 26-26 of the guide means 24 is partially cut away or reduced to define an inclined surface portion 62. The angle between the portion 62 and the longitudinal axis AA of the housing 12 equals the angle between the other inclined side portion 26 of the guide means 2 1 and the axis AA of the housing 12. By constructing the guide means 24, the positioning of the actuator arm 13 will change readily and easily from the first or initial position shown in FIGURE 1 to the second and third positions shown in FEGURE 2 and FIGURE 3, respectfully.

Each of the snap action type switches 32 and 34 is a spring-loaded single pole, double-throw switch. Schematically, the switches 32 and 34 are illustrated in FIG-- URES a, 5b and 5c. The switch 34 contains a movable contact arm 64 for connecting a contact terminal A to one or the other of contact terminals B-C. The switch 32 contains a movable contact arm 66 for connecting a contact terminal D to one or the other of contact terminals EF. The contact terminals A through F cor respond with the similarly lettered terminals shown in FIGURE 4 of the drawing. Both of the arms 64 and 66 are spring biased. In FIGURE 5a the arm 64 is shown in its normally biased position and the arm 66 is shown in its other position away from its normally biased position.

The switch operating plungers 56 and 54 actuate the movable contact elements 64 and 66 of the switches 34 and 32, respectively. FIGURE 5a shows the positions of the contact elements 64 and 66 at the moment the sensor actuator arm 18 is in the position shown in FIG- URE 1, with the plunger 54 being depressed and the plunger 56 being released. FIGURE 5b shows the positions of the contact elements 64 and 66 at the moment the sensor actuator arm 18 is in the position shown in FIGURE 2, with the plungers 54 and 56 both being released. FIGURE 5c shows the positions of the contact elements 64 and 66 at the moment the sensor actuator arm 18 is in the position shown in FIGURE 3, with the plunger 54 being released and the plunger 56 being depressed.

As illustrated in FIGURE 4 of the drawing, the terrninals A through F are supported by a cover 68 at the other end portion of the housing 12. In FIGURE 1, the electrical connections between the terminals A through F and the connecting terminals of the switch devices 32 and 34 have been omitted to simplify the drawing.

The switch devices 32 and 34 control the operation of electrical circuits, not shown. The electrical circuits may be used for controlling various functions such as producing the command signals for use in a missile, as disclosed at the beginning of the descriptive portions of the specification. The switch device 34 may be used to produce a command signal for arming the missile, and the swicth device 32 may be used to produce a command signal for separating a nose cone from an engine after burnout. Gne side of each of the switch devices is for the primary switching function, and the other side of each switch device is for electrical monitoring. The purpose of the sequence acceleration sensor is to operate the switches 32 and 34 according to a predetermined acceleration profile of a vessel, projectile, missile, or the like.

In FIGURE 6 of the drawing, a curve of the accelera tion profile of a projectile such as a missile is shown, wherein gravitational force G is plotted against time T. As the missile leaves the launching pad, it gradually increases in acceleration to a predetermined G-value indicated by G1, increases more rapidly to a G-value indicated by G2, and reaches a near maximum G-value at G3. After the missile has accelerated through the G- value at G3, it begins to decelerate, again passing through the value G2.

In operation, the sequence acceleration sensor 16 is mounted on the missile and is designed to operate the switches 32 and 34 in sequence in accordance with the acceleration profile shown in FIGURE 6. Before launching the missile, the actuator arm 18 is in the first or initial position shown in FIGURE 1, and the operating plunger 54 of switch 32 is depressed to hold the switch contact element 66 against the spring bias preload in the position shown in FIGURE 5a. The operating plunger 56 of the switch 34 is released, and the switch contact element 64 is preloaded by its spring bias in the position shown in FIGURE 5a.

When the missile leaves the launching pad and the sensor 10 is subjected to an increasing positive acceleration, the movable mass structure 14 will be urged and will pass along the given course that is substantially common with the longitudinal axis AA of the housing and 6 will overcome the force created by the first biasing means 16 and reduce the preload condition thereof. Upon reaching the valve of acceleration at G1, the mass structure 14 moves along the given course A-A relative to the housing 12 allowing the actuator arm 18 to release the plunger 54 and the switch 66, with the arm 18 sliding along the adjacent side portion 26 of the guide means 24 but not beyond the apex thereof. At this moment, the actuator arm 18 still is within the confines of the portion 50 of the space 28 between the guide means 24 and the adjacent portion of the housing 12, and is laterally or transversely biased against the adjacent side portion 26 by the force created by the second biasing means 22.

With increasing acceleration of the missile to G2, and on reaching the near maximum value acceleration G3, as the case may be, the actuator arm 18 is withdrawn from the portion 50 of the space 28 and as the actuator arm 18 clears the apex 30 of the guide means, 24, the second biasing means 22 snaps the bar actuator arm 18 laterally against the stop 58. The switch contact elements 64 and 66 remain in the positions shown in FIGURE 511 because the switch operating plungers 54 and 56 both still are released.

After passing through the valve of acceleration G3, and on return to the valve such as G2, the actuator arm 18, which has entered the portion 52 of the space 28 between the other side portion 26 of the guide means 24 and the adjacent portion of the housing 12 and has slid easily along the reduced portion 62 thereof to fully depress the operating plunger 56 of the switch device 34. The switch contact element 64 is moved against its preload into the position shown in FIGURE 50, with the switch 66 remaining unchanged. The magnitude of the axial preload upon the actuator arm 18 is determined by the first biasing means 16, and may be varietd by changing the number of shim elements 48 between the spring retraining place 46 and the one end portion of the housing The location of the actuator arm 18 is set initially, or reset, in the following manner. The screw caps 36 and 38 are removed from the housing 12. A rod-like tool having a threaded end, not shown, is inserted into the aperture uncovered by the removal of the cap 36 and screwed into the slot 42 in the recess 44 in the back of the piston member which is then pulled to a fully retracted position. Another rod-like tool, not shown, is inserted into the aperture uncovered by the removal of the cap 38. The actuator arm 18 is pushed laterally by this other tool, and the piston-like member 449 then is released and returns to the normal position, placing the actuator arm 18 in ready position as shown in FIGURE 1 of the drawing.

While the sequence acceleration sensor 16 has been shown, illustrated, described and disclosed as being provided with the switch devices 32 and 34, it is to be understood that other types of arrangements may be employed with the sensor 10 which will be responsive to and actuated by the actuator arm 18 in a manner similar to that as described and disclosed above.

While the invention has been described, disclosed, illustrated and shown in terms of a preferred embodiment which it has assumed in practice, the scope of the invention should not be deemed to be limited by the precise embodiment herein shown, described, illustrated and disclosed, such other embodiments, modifications, procedures or equivalents are intended to be reserved as they fall within the scope of the claims here appended.

We claim as our invention:

1. A. acceleration sensor comprising,

an elongate hollow housing,

mass structure supported within the hollow of the housing adjacent one end portion thereof for logitudinal movement along a given course toward and away from the other end portion of the housing in response to changes in acceleration,

said mass structure comprising a piston-like member and a bias disposed intermediate the piston-like member and the one end portion of the housing for urging the piston-like member along the given course toward the other end portion of the housing,

an elongate actuator arm supported by the piston-like member and projecting therefrom within the hollow of the housing toward the other end portion thereof,

means pivotably mounting the actuator arm to the piston-lihe member for movement generally laterally relative to the given course,

elongate guide means carried adjacent the other end portion of the housing and projecting generally longitudinally inwardly into the hollow thereof toward the mass structure with the guide means being disposed generally along the given course in laterally spaced relationship relative to the adjacent portion of the housing to define therewith a space disposed to laterally opposed sides of the given course,

said guide means being of wedge shape in configuration having converging side portions terminating in an apex,

a switch device supported by the guide means to opposed sides of the longitudinal axis at locations thereon which are adjacent to the space,

said actuator arm being operable to be initially positioned in a portion of the space to actuate the switch device which is adjacent thereto and sequentially withdrawn from that portion of the space and movable to another portion thereof which is to the opposite side of the given course whereat said actuator arm may actuate the switch device associated with the other portion of the space, and

biasing means for generally laterally pivotally moving the actuator arm from the one side to the other side of the given course.

2. The acceleration sensor as set forth in claim 1 wherein the apex of the guide means is offset to one side of the given course. 3. The acceleration sensor as set forth in claim 1 wherein the side portion of the guideimeans which is disposed to the opposite side of the given course is reduced adjacent the apex.

4. The acceleration sensor as set forth in claim 1 wherein said housing has an aperture through an end wall thereof which is adjacent the one end portion for receiving a tool to adjust the longitudinal position of the mass structure relative to the given course, and

another aperture through a side wall of the housing for receiving a tool to adjust the lateral position of the actuator arm relative to the given course.

5. An acceleration sensor comprising,

mass structure supported'for movement along a given course in response to changes in acceleration,

an actuator arm pivotally supported by the mass structure and projecting therefrom for movement generally laterally relative to the given course,

elongate guide means disposed generally along the given course for defining a space disposed to laterally opposed sides of the given course,

said guide means having side portions which converge relative to each other and terminate in an apex which is disposed laterally to oneside of the given course with the side portion which is to the opposite side of the given course being reduced adjacent the apex,

an arrangement supported by the guide means to opposed sides of the given course at locations therealong which are adjacent to the space,

said actuator arm being operable to be initially positioned in a portion of the space to actuate the arrangement which is adjacent thereto and sequentially withdrawn from that portion of the space and movable to another portion thereof which is to the opposite side of the given course whereat said actuator arm may actuate the arrangement associated with the other portion of the space, and

means for generally laterally pivotally urging the actuator arm from one side to the other side of the given course.

'6. An acceleration sensor comprising,

a housing,

mass structure supported by the housing for movement along a given course in response to changes in acceleration,

said mass structure comprising a piston-like member and a bias disposed intermediate the piston-like member and the housing for urging the piston-like member along the given course, i

an actuator arm projecting from the piston-like member,

means pivotably mounting the actuator arm to the piston-like member for movement generally laterally relative to the given course,

elongate guide means carried by the housing and projecting therefrom generally toward the mass structure with the guide means being disposed along the given course in laterally spaced relationship relative to the adjacent portions of the housing to define therewith a space disposed to laterally opposed sides of the given course,

said guide means having side portions which converge relative to each other in a direction toward the mass structure and terminate in an apex disposed laterally to one side of the given course,

an arrangement supported by the guide means to opposed sides of the given course at locations therealong which are adjacent to the space,

said actuator arm being operable to be initially positioned in a portion of the space to actuate the arrangement which is adjacent thereto and sequentially withdrawn from that portion of the space and movable to another portion thereof which is to the opposite side of the given course whereat said actuator arm may actuate the arrangement which is associated with the other portion of the space, and

' biasing means for generally laterally pivotally urging the actuator arm from the one side to the other side of the given course. 7. The acceleration sensor as set forth in claim 5 wheresaid last named means comprises a spring interposed between the mass structure and the actuator.

References Cited by the Examiner UNITED STATES PATENTS BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner, 

1. A ACCELERATION SENSOR COMPRISING, AN ELONGATE HOLLOW HOUSING, MASS STRUCTURE SUPPORTED WITHIN THE HOLLOW OF THE HOUSING ADJACENT ONE END PORTION THEREOF FOR LOGITUDINAL MOVEMENT ALONG A GIVEN COURSE TOWARD AND AWAY FROM THE OTHER END PORTION OF THE HOUSING IN RESPONSE TO CHANGES IN ACCELERATION, SAID MASS STRUCTURE COMPRISING A PISTON-LIKE MEMBER AND A BIAS DISPOSED INTERMEDIATE THE PISTON-LIKE MEMBER AND THE ONE END PORTION OF THE HOUSING FOR URGING THE PISTON-LIKE MEMBER ALONG THE GIVEN COURSE TOWARD THE OTHER END PORTION OF THE HOUSING, AN ELONGATE ACTUATOR ARM SUPPORTED BY THE PISTON-LIKE MEMBER AND PROJECTING THEREFROM WITHIN THE HOLLOW OF THE HOUSING TOWARD THE OTHER END PORTION THEREOF, MEANS PIVOTABLY MOUNTING THE ACTUATOR ARM TO THE PISTON-LIKE MEMBER FOR MOVEMENT GENERALLY LATERALLY RELATIVE TO THE GIVEN COURSE, ELONGATE GUIDE MEANS CARRIED ADJACENT THE OTHER END PORTION OF THE HOUSING AND PROJECTING GENERALLY LONGITUDINALLY INWARDLY INTO THE HOLLOW THEREOF TOWARD THE MASS STRUCTURE WITH THE GUIDE MEANS BEING DISPOSED GENERALLY ALONG THE GIVEN COURSE IN LATERALLY SPACED RELATIONSHIP RELATIVE TO THE ADJACENT PORTION OF THE HOUSING TO DEFINE THEREWITH A SPACE DISPOSED TO LATERALLY OPPOSED SIDES OF THE GIVEN COURSE, SAID GUIDE MEANS BEING OF WEDGE SHAPE IN CONFIGURATION HAVING CONVERGING SIDE PORTIONS TERMINATING IN AN APEX, A SWITCH DEVICE SUPPORTED BY THE GUIDE MEANS TO OPPOSED SIDES OF THE LONGITUDINAL AXIS AT LOCATIONS THEREON WHICH ARE ADJACENT TO THE SPACE, SAID ACTUATOR ARM BEING OPERABLE TO BE INITIALLY POSITIONED IN A PORTION OF THE SPACE TO ACTUATE THE SWITCH DEVICE WHICH IS ADJACENT THERETO AND SEQUENTIALLY WITHDRAWN FROM THAT PORTION OF THE SPACE AND MOVABLE TO ANOTHER PORTION THEREOF WHICH IS TO THE OPPOSITE SIDE OF THE GIVEN COURSE WHEREAT SAID ACTUATOR ARM MAY ACTUATE THE SWITCH DEVICE ASSOCIATED WITH THE OTHER PORTION OF THE SPACE, AND BIASING MEANS FOR GENERALLY LATERALLY PIVOTALLY MOVING THE ACTUATOR ARM FROM THE SIDE TO THE OTHER SIDE OF THE GIVEN COURSE. 